One prior push button type fastener of this kind is described in a publication of a Japanese Patent 57-8323.
This push button type fastener 100, which is shown in FIG. 7, includes a stud assembly 101 that is attached to a moving side panel 20a and a socket 103 that is attached to a fixed side panel 30a. The stud assembly includes a stud 110 whose configuration has a wall portion 112 extending to a cylindrical portion 111 and a cam 114 extending from the wall portion 112 in a twisted relation via a distal portion 113, as shown in FIG. 8, and further includes a housing 120 in which the stud 110 is inserted. The stud 110 is urged upwardly by means of a compression spring 104, which is interposed between the head portion thereof and the bottom portion 121 of the housing 120. The stud is fixed to the moving side panel 20a with a fixing ring 105, which engages the flange 122 of the housing 120.
The socket 103 is provided with a pair of resilient arms 131 which gradually approach each other downwardly from a pair of the sides of a base portion 130 which is disposed in parallel with the fixed side panel 30a. Extended portions (not shown) for attaching the socket 103 to the back of the lower panel 30a by rivets or the like are extended from the other sides of the lower panel which are not provided with the arms 131. On the ends of the arms 131, after gradually approaching close to each other, stopping portions 132 which are parallel with the lower panel 30a are formed.
In order that both the panels 20a and 30a can be fastened together by the push button type fastener 100, firstly, the moving side panel 20a is overlapped on the fixed side panel 30a, and the stud 110 is pushed in the reverse direction of the pushing force of the spring 104, so that the cam 114 is guided along the inner surfaces of the resilient arms 131 and the tips of the resilient arms are pushed open. Thereafter, the distal portion 113 is passed through the opened portion with opening it further, so that the opposing flat surfaces of the wall portion 112 are rotated in such a manner that they are gripped between the resilient arms 131. Then, the pushing force for the stud 110 is released, so that the engaging surfaces 115 of the distal portion 113 are engaged with the stopping surfaces 132' of the stopping portions 132 so as not to be disengaged, as shown in FIG. 7, whereby the panels 20a and 30a are fastened to each other.
In order to open the moving side panel, the stud is rotated about 90.degree. by using a driver or the like that engages the groove 123 of the tip of the stud. Then, as the tips of the resilient arms 131 are opened by the wall portion 112, wide enough to pass the distal portion 113, the stud 110 is drawn upwardly by the spring 104, whereby the moving side panel 20a can be opened.
In such a push button type fastener, however, it is disadvantageous that the stud must be rotated about 90.degree. for its releasing action. In addition, machining is difficult because of the complicated configurations of the stud 110 and the tip of the socket.
Furthermore, it is disadvantageous that the stud assembly 101 and the socket 103 need fixing means such as the fixing ring 105 or the rivets or the like for attaching them to their respective panels. An excessive number of the parts is required, and an excessive amount of time is required to assemble them.